This invention relates generally to rear-screen film-slide projection arrangements, and more particularly to a mobile, audio-visual system which includes a multiscreen matrix on which there are displayed images selectively derived from an array of programmed slide projectors.
In order to present film slides in a continuous sequence, existing slide projectors employ slide trays in conjunction with an indexing mechanism adapted to transfer the slides successively into an optical path for projection. Thus in slide projectors manufactured by Eastman Kodak Company under the trademark "Carousel" and "Ektagraphic," the slide tray is in the form of a turntable that is indexed to successively project slides withdrawn from the circular array thereof. A description of a Kodak Ektagraphic Slide Projector Model AF may be found in the Eastman Kodak publication of January 1969, RPP-AX pub. pt. no. 634402.
In a conventional front-view projector, the picture is cast onto the front of a screen erected at a suitable distance from the projector. This arrangement is generally acceptable in a home where the room may be darkened and the screen may be conveniently placed therein. However, the viewability of an illuminated visual image is determined in large measure by contrast with its background. In front-view projection, the screen brightness is directly affected by ambient lighting conditions, and in a brightly-lit room it is virtually impossible to see the image.
To overcome the drawbacks of front-view screen projection, rear-screen projectors have been developed which make viewing feasible under relatively bright ambient conditions. Thus the prior Schwartz Pat. No. 3,560,088 discloses a projection theater in which images from a slide projector are directed onto an inclined mirror which reflects the images upwardly toward a second inclined mirror, the second mirror, in turn, casting the images onto the rear of a translucent screen.
It is also known to provide an audio-visual system making use of an array of rear-view screen slide projector theatre units which are joined together so that the screens form the sections of a large matrix. Thus the Multi-Visual Synthesizer developed by Motiva, Ltd. and described in the June 1972 issue of "Exhibit" magazine makes use of an assembly of rear-view slide projection units, each housing a standard Eastman Kodak slide projector. The slide projectors in the array are selectively and individually controlled by a punched-tape programmer in tandem with high-fidelity amplifiers and continuous loop cartridge tape-playback machines.
The system disclosed in "Exhibit" is formed by a multi-section screen matrix of fifteen slide projectors controlled by the respective channels of the punched tape programmer. Each channel acts to activate the associated projector in accordance with the program therefor defined by a track of punch holes. For example, if on a given transverse line on the multi-channel tape, there is a punch hole in each of the fifteen channels, then when this line reaches the read-out device, all fifteen projectors are simultaneously actuated. But if at this line there is a punch hole, say only for the third, fifth and ninth projectors, then only these projectors are actuated when the line is reached.
Thus at a given time, the screen matrix may have a different image displayed in each section thereof, or only selected sections may be activated to create a pattern of images, the other sections then being blank. At other times in the course of a program, all sections of the matrix may be activated to display a single, highly-enlarged sectioned image, each projector supplying a respective section of the total image. With multiple slide-projector units and a programmer having a distinct channel to choreograph the effects produced by the units as well as a channel to coordinate therewith the accompanying stereophonic sound, it becomes possible to create audio-visual effects in which image sequencing, patterning and counterpoint are correlated with sound or background music.
Because of the rear-projection arrangement, a Motiva Multivisual Synthesizer is usable under high ambient-lighting conditions, such as in shopping center malls, building lobbies and exhibit areas. And because the system is capable of continuous and unattended operation, it is particularly suitable for situations where people enter and leave at random intervals, such as in museums and side shows.
Though an audio-visual system of the known type is useful in many aspects of communication, including sales promotion, education and entertainment, it suffers from one serious practical drawback. This drawback resides not in the cost of purchasing or leasing the system, which is modest, but in the expenses involved in installation. A system of the type heretofore known lacks mobility and cannot be wheeled into a truck for transportation. Nor can the system be passed through a typical doorway (about 34 inches wide).
Hence it was heretofore the practice to ship the required number of slide projection theatre units to the site where they were assembled to create the desired matrix, and to set up at the site and wire-in the necessary programmer, audio amplifier, speakers and tape play-back machine. This installation procedure was time-consuming and costly, and therefore discouraging to many potential users of the audiovisual slide projection system.